1. Technical Field of the Invention
This invention relates to electrical connectors and, in particular, to an interference fit contact pin having a conditioning section for preparing various sized plated-through holes to receive the contact pin compliant section.
2. Description of the Prior Art
In many circuit applications there is a need to interconnect conductors and components to conductive paths either within or on a printed circuit board. Relatively recent developments to satisfy this need have centered around interconnection pins which are inserted into plated-through holes in the circuit board and held there by frictional engagement of the pin with the hole periphery.
One illustration of a frictional fit pin of this type is disclosed in U.S. Pat. No. 3,223,960 issued to H. E. Ruehlemann on Dec. 14, 1965. Ruehlemann relates to a contact with waveshaped tail sections. The contact is comprised of a body section, a mating section and a tail section projecting from the body section. The tail section includes a substantially uniplanar root which has a pair of edges extending to the body section. Extending away from at least one of the edges is an integral locking wing.
Another example of a connector of the type under consideration is set forth in U.S. Pat. No. 3,783,433 issued to H. N. Kurtz et al on Jan. 1, 1974. Kurtz et al disclose a solderless electrical connection system wherein a main mounting board is provided with a plurality of plated-through holes. A conductive electrical contact, including a central section, is pressed into the plated-through hole with the central section flexing as it is urged into the hole and yielding to generate retention forces without destroying the hole. Each end of the conductive contact is provided with a configuration which allows electrical components to be mounted thereon or attached thereto.
A somewhat related connection system to those noted above is set forth in U.S. Pat. No. 3,825,876 issued to N. F. Damon et al on July 23, 1974. Damon et al disclose an electronic component mounting system adapted for the high density packaging of integrated circuits. Each integrated circuit component is rigidly attached to a complementary cartridge of insulative material. The assembled structure is inserted in either normal or inverted position within terminals correspondingly arrayed on a mounting panel. In the normal position the assembly may be plugged in and snapped out as required, while in the inverted position the individual leads of the integrated circuit may be soldered to respective terminals. Each of the mounting panel terminals is provided with a wirewrapping pin extension.
Still another illustration of printed circuit board connectors is disclosed in U.S. Pat. No. 3,871,728 issued to D. S. Goodman on Mar. 18, 1975. Goodman relates to a matched impedance printed circuit board connector which is comprised of a housing mounted on a mounting board having a ground plane and signal traces separated by an insulator. A grounding bus extends lengthwise in the housing below the printed circuit board receiving slot. Signal contacts in the housing are mounted in plated-through holes in the mounting board which contacts are connected to the signal traces. The grounding bus has mounting portions which are mounted in other plated-through holes in the board and which are joined to the ground plane. Ground contacts are also provided in the housing which are mounted in additional plated-through holes joined to the ground plane so that the ground contacts and grounding bus are electrically interconnected.
A further example of printed circuit board connectors of the type under discussion is disclosed in U.S. Pat. No. 4,017,143 issued to R. G. Knowles on Apr. 12, 1977. Knowles relates to a solderless electrical contact which has first and second ends for connection to conductive elements. These ends are joined by a central section having a C-shaped cross section with opposing arms tapered to a reduced end thickness for press-fit mounting into a printed circuit board aperture. The tapering arms of the C-shaped cross section provide uniformly stressed beams that allow the radii of each arm to conform to tolerance variations of the aperture.
Still another illustration of an interference-fit printed circuit board connector is set forth in U.S. Pat. No. 4,076,356 issued to P. J. Tamburro on Feb. 28, 1978. Tamburro discloses an interconnection pin for connecting multiple conductive layers in a printed circuit board to one another. The connector includes a pair of elongated electrical terminals and a compliant section therebetween. A plurality of generally parallel raised pressure ridges are included on an outer surface of the compliant section. The connector may be advantageously divided into a plurality of semiseparate segments thereby enabling interconnection of an axially aligned stack of printed circuit boards.
Yet another example of circuit board connectors is disclosed in U.S. Pat. No. 4,077,694 issued to R. F. Cobaugh et al on Mar. 7, 1978. Cobaugh et al disclose a connector having a plurality of pairs of contacts arranged in a row and with each contact having a C-shaped portion. Each pair of contacts is mounted securely at first ends in a circuit board with the backs, or closed sides, of the C-shaped portion facing each other and designed to receive the edge of a second circuit board inserted therebetween.
Each of the connectors described above has the disadvantage of not being capable of preconditioning the plated-through hole prior to engagement of the interference-fit section of the connector with the hole periphery. In most instances this deficiency results from a relatively smooth or tapered transition section between the compliant portion of the connector and its terminal end. Heretofore such a smooth or tapered transition section has been a design goal since it was generally believed that any other design might give rise to damage of the plated-through hole. Hence, one of the problems experienced with interference-fit connectors has been and continues to be the proper preconditioning of the plated-through hole so that maximum retention forces can be achieved.
Another problem experienced with interference-fit connectors is their inability to remove any insulative oxide layers which may coat the inner periphery of the plated-through hole. Such layers can cause a degradation in the quality of the electrical contact between the plated-through hole and the compliant section.